Optical fibres are glass or plastic fibres designed to guide light along their length by confining as much light as possible in a propagating form. They are widely used in fibre-optic communication, which permits transmission over long distances and high data rates. They are also used to form sensors, and in a wide variety of other applications.
As sensors optical fibres can be used to measure strain, temperature, pressure and other parameters. The small size and the fact that no electrical power is needed at the remote location give the fiber optic sensor advantages over conventional electrical sensors in certain applications. Another advantage is that optical fibres function at very high temperatures and can therefore be used in very high temperature environments, which have, for example, temperatures that are too high for semiconductor sensors to function properly.
Optical fibre sensors have been developed for use in oil, gas or other wells to measure temperature, pressure and other parameters down-hole. Most wells where optical fibres are used have high temperatures of operation which are above 125 degrees Celsius. Many of these wells are heavy oil wells, where the installation of fibre optics is preferred for their use in high temperature environments as they are often used to monitor the temperatures required when steam injection is used to lower the viscosity of the heavy oils.
There are two ways in which to deploy the optical fibre into wells. One way is to deploy the optical fibre through a small metal or high temperature plastic tube, and the tube can then be installed into a well before or after the optical fibre is deployed. Another way is to install the optical fibre cable directly into a well. The optical fibre cable is formed from optical fibres which are inside a metal tube. The optical fibre cable can contain one or several optical fibres. In the first case, optical fibre is continuously installed into the well, but in the second case there is a minimum of one optical fibre splice needed to be made in order to connect the down hole cable and optical fibre sensor together. Carbon coated polyamide optical fibres have been widely used in oil wells which have high temperatures of above 125 degrees Celsius.
Currently when a splice is made on an optical fibre that is to be used directly down-hole in a well, the bare fibre splice is left without any protection after the splice is made. The reason for this is that currently available optical fibre protectors cannot operate at the very high temperatures which are present in wells.
One of the advantages provided by the current invention is that an optical fibre splice protector is provided that can be used in very high temperatures and thus can protect optical fibre splices which are in very high temperature and chemically corrosive environments such as, for example, down-hole in wells. The optical fibre splice protector of the current invention is light, flexible and, as it has its own internal support; it does not require the splice to be supported separately after it has been applied to the optical fibre. In addition, the splice protector can be made on a very small scale and it can easily be integrated with small fibre coils.